Method and device for rounding brush bristles



May 21, 1968 D. A. GuY ET AL 3,384,418

METHOD AND DEVICE FOR ROUNDING BRUSH BRISTLES Filed March 8, 1966 2 Sheets-Sheet 1 Inn/1140's Uaaie/ us Maan'ce, HM- Pie}.

May 21, 1968 U ET AL 3,384,418

METHOD AND DEVICE FOR ROUNDING BRUSH BRISTLES Filed March 3, 1966 2 Sheets-Sheet :1

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United States Patent 3,384,418 METHOD AND DEVICE FOR ROUNDING BRUSH BRISTLES Daniel A. Guey and Maurice A. M. Briez, Beauvais, Oise,

France, assignors to La Brosse et J. Dupont Reunis,

Paris, France, a corporation of France Filed Mar. 8, 1966, Ser. No. 532,670 Claims priority, application France, Mar. 15, 1965,

9,308 12 Claims. (Cl. 300-21) ABSTRACT OF THE DISCLOSURE In carefully manufactured brushes, more particularly toothbrushes comprising very strong synthetic fibres such as polyamides, the bristle ends are of course rounded to remove the sharp edges, splinters or burr produced when the bristles are cut up.

It is an object of the invention to provide a method and device for performing rounding of the kind specified rapidly and with very satisfactory results. To this end, according to the invention the bristle ends are given a treatment preferably comprising the following successive stages: a roughing-out by machining on a rough surface whose extent in relation to the bristle ends varies constantly at the place where the bristles contact the rough surface; deburring by repeated impacts produced in all directions by rough-surfaced blunt elements moving rapidly in relation to the bristle ends; and a polishing or burnishing treatment, also performed by repeated impacts produced in all directions, this time by means of blunt elements which have polished surfaces and also move at a relatively high velocity in relation to the bristle ends.

Advantageously, the treatment according to the invention is performed after the bristles have been inserted in the brush, which is then placed in a brush-bearing member which enables the brush to rotate on itself to offer its bristle ends at all angles to the rough surface and impacting elements, the result being very regularly rounded bristle ends. Preferably, the rough surface is corrugated at the place where the bristle ends bear thereagainst, and during the roughing-out operation the bristle ends are moved transversely of the corrugations. For instance, the rough surface can be a rotary disc formed with furrows which are eccentric of the axis of rotation and against which the bristle ends bear, the brush rotating around a fixed axis parallel with the axis of rotation of the disc.

The other operations can also be performed by means of rotary discs having impacting elements such as needles, which are advantageously disposed in concentric rows eccentric of the axis of rotation of the disc, the brush also being preferably so mounted as to rotate around an axis parallel with the axis of rotation of the disc.

The invention covers the method of treatment, the devices used for performing the treatment, the novel industrial products formed by bristles rounded by the application of the method according to the invention by means of at least one of its component devices, and

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brushes or other articles comprising bristles of the kind specified.

The invention is illustrated by way of example in the accompanying drawings, in which:

FIG. 1 is a plan view of a roughing-out disc according to the invention,

FIG. 2 is a section, taken along the line IIII in FIG. 1, also showing diagrammatically the mounting of the brush whose bristles are tobe rounded,

FIG. 3 is a plan view of a disc for performing the deburring or polishing operations, in dependence on the kind of needles with which the disc is equipped,

FIG. 4 is a section, taken along the line IVIV in FIG. 3, also showing the mounting of the brush,

FIG. 5 is a partial view, to an enlarged scale, of a disc having rough ended needles, and

FIG. 6 is a view similar to FIG. 5 of a disc having needles with smooth and polished ends.

A brush 1, whose bristles 2 are to be rounded, is mounted in a brush-bearing member 3 rotated by a motor 4 around an axis A (FIG. 2). Disposed opposite the bristle ends is a rough surface 5 having corrugations 6 with rounded crests and troughs. The rough surface 5 rubs against the ends of the bristles 2, while the corrugations move transversely of the bristle ends to attack them at an ever-varying angle and thus give them a regular rounded or ogival shape, in combination with the rotation of the brush. The amplitude of the transverse movement is slightly greater than the width of the corrugations.

In the exemplary embodiment shown in FIGS. 1 and 2, the surface 5 forms part of one of the surfaces of a disc 7 rotated by a motor 8 around an axis B parallel with the axis A. The corrugations 6 take the form of circular furrows with which the disc 7 is formed. The furrows have a uniform width e and are centred on a point 0 (FIG. 1) which is at a distance d from the axis B slightly greater than half the width e. For the usual type of modern toothbrush, the width e can have a value of approximately between 6 and 12 mm., d can have a value of approximately between 4 and 8 mm., and the maximum depth of the furrows can be approximately 2-4 mm. Of course, these values are merely exemplary. The rough surface is preferably made of steel which has been hardened by tempering followed by hard chrome plating to produce a Vickers surface hardness of about 18002000. The corrugated zone of the disc against which the bristles bear for rounding is roughened by sandblasting with sand having a grain size which can vary between 30 and 80, the grain size being defined by the number of wires per inch (25.4 mm.) of the smallest standard sieve through which the grain can pass. In the embodiment illustrated, the corrugated zone of the disc lies between two circumferences, whose radii are about 60-80 mm. and -150 mm. The speed of rotation of the disc is in the order of 950-2800 rpm.

The brush can rotate on itself at a speed of 60-120 r.p.m. and be applied to the disc for a period during which the brush performs a certain number, for instance 28 revolutions. The precise speeds to be used can be determined by tests made in each particular instance.

After the roughing-out treatment, the brush can be given a deburring treatment by repeated impacts produced in all directions by impacting elements moving at relatively high velocities. In the embodiment illustrated in FIGS. 3-5 the impacting elements are needles having rounded ends and inserted in a rotary disc 10 driven by a motor 11 (FIG. 4).

The needles 12 are disposed in concentric and eccentric semicircles Whose centres D and D are symmetrical of the centre 0 of the disc 10 (FIG. 3). For instance, the

semicircles are at a distance of about 5 mm. from one another, the radii for the smaller circles varying from about 60-80 mm. and for the larger semicircles from about 110-130 mm. The eccentricity can be, for instance, 4-8 mm. The dimeter of the needles can vary from about 1-5 mm.

To perform the deburring operation the ends 13 of the needles 12 are roughened by sandblasting performed, as in the case of the disc 7, with sand whose grain size varies from about 30-80.

The brush l to be treated is mounted in a brush-bearing member 14 disposed in front of the ring of needles and rotated by a motor 15 around an axis E parallel with the axis F of the disc 10. In dependence on the shape of the brush tuft and the nature and size of the bristles, the disc can be driven at speeds of between about 1400 and 3500 rpm. and the brush-bearing member can rotate at about 60-120 -r.p.m., the brush performing 4-12 revolutions in contact with the disc. The needles l2 deburr the rounded bristle ends roughed out by the disc 7.

The third operation, namely the final polishing or burnishing, is performed with a disc and brush-bearing member which are identical with those described hereinbefore, except that the ends 13a of the needles 12 are completely smooth (FIG. 6).

The size and arrangement of the needles, and also the speeds of rotation of the disc and the brush-bearing member can be the same as in the deburring operation.

We claim:

1. A method of rounding brush bristles, wherein the bristle ends are first given a roughing-out treatment by machining on a surface whose extent relatively to the bristle ends varies constantly at the place where the bristles contact the surface, whereafter the roughed-out bristle ends are given a polishing treatment by repeated impacts produced in all directions by blunt elements moving at a relatively high velocity in relation to the roughed-out bristle ends.

2. A method as set forth in claim 1, wherein after the roughing-out treatment, but before the polishing treatment, deburring is performed by repeated impacts produced in all directions on the roughed-out bristle ends by blunt rough-surfaced elements moving at a relatively high velocity in relation to the roughed-out bristle ends, the polishing whereof is performed by blunt elements having polished surfaces.

3. A method as set forth in claim 1, wherein the roughing-out treatment is performed by rubbing the bristle ends on a corrugated rough surface so driven that the corrugations traverse longitudinally and oscillate transversely in relation to the bristles, which are also rotated around an axis substantially perpendicular to the corrugated rough surface.

4. A method as set forth in claim 1, wherein the roughing-out treatment is performed by rubbing the bristle ends on a corrugated rough surface so driven that the corrugations traverse longitudinally and oscillate transversely in relation to the bristles, which are also rotated around an axis substantially perpendicular to the corrugated rough surface, the amplitude of the oscillations being not less than the width of the corrugations.

5. A device for roughing-out the rounding of brush bristles, comprising a corrugated rough surface, means for traversing the corrugated rough surface in front of a rotary brush-bearing member and in contact with the ends of the bristles of a brush mounted therein, and means for making the corrugations perform a transverse oscillatory movement in relation to the bristles.

6. A device as set forth in claim 5, wherein the rough surface is formed by a rotary disc having furrows forming concentric corrugations whose common centre is not on the axis of rotation of the disc.

7. A device as set forth in claim 5, wherein the rough surface is formedby a rotary disc having furrows forming concentric corrugations whose common centre is not on the axis of rotation of the disc, and the axis of rotation of the brush-bearing member is parallel with the axis of rotation of the disc and extends through the corrugated zone thereof.

8. A device as set forth in claim 5, wherein the rough surface is formed by a rotary disc having furrows forming concentric corrugations whose common centre is not on the axis of rotation of the disc, and the eccentricity of the corrugations is at least equal to half the width of the corrugations.

9. A device as set forth in claim 5, wherein the rough surface is formed by a rotary disc having furrows forming concentric corrugations whose common centre is not on the axis of rotation of the disc, and the corrugated surface of the disc is made of hard metal roughened by sandblasting.

10. A device for performing the complementary treatment of brush bristle ends to be rounded, comprising a rotary disc, a plurality of blunt imparting elements disposed on the disc in concentric rows which are eccentric of the disc axis, and a brush-bearing member spaced from said blunt impacting element and rotatable around an axis substantially perpendicular to the direction of traversing of the blunt elements, so that the latter can impact in all directions the ends of the bristles of a brush mounted in the brush-bearing member.

11. A device as set forth in claim 10, wherein said concentric rows are formed by eccentric semicircles symmetrical of the axis of rotation of the disc.

12. A device as set forth in claim 10, wherein the impacting elements have rough ends.

References Cited UNITED STATES PATENTS 1,627,704 5/1927 Izawa. 2,017,487 10/1935 Elliot. 2,227,126 12/ 1940 Cooke.

FOREIGN PATENTS 507,794 11/1954 Canada.

WILLIAM W. DYER, JR., Primary Examiner.

GRANVILLE Y. CUSTER, JR., Examiner.

R. L. FARRIS, Assistant Examiner. 

